Cold climate-driven convergent evolution among angiosperms.

Convergent and parallel evolution occur more frequently than previously thought. Here, we focus on the evolutionary adaptations of angiosperms to sub-zero temperatures. We begin by introducing the research history of convergent and parallel evolution, defining all independent similarities as convergent evolution. Our analysis reveals that frost zones (periodic or constant), covering 49.1% of Earth's land surface, host 137 angiosperm families with over 90% of their species thriving in these regions. On this context, we revisit the global biogeography and evolutionary trajectories of plant traits, such as herbaceous form and leaf deciduousness, which are likely evasion strategies for frost adaptation. At the physiological and molecular levels, many angiosperms have independently evolved cold-acclimation mechanisms through multiple pathways beyond the well-characterized CBF/DREB1 regulatory pathway. The convergent adaptations occur across various molecular levels, including amino acid substitutions and changes in gene duplication and expression within the same or similar functional pathways; however, identical amino acid changes are rare. Moreover, we highlight the prevalence of polyploidy in frost zones and occurrence of paleopolyploidization events during global cooling. These patterns suggest repeated evolution in cold climates. Finally, we discuss plant domestication, predict climate zone shifts due to global warming, and their effects on plant migration and in-situ adaptation. Overall, integrating ecological and molecular perspectives is essential for understanding and forecasting plant responses to climate change.